Device having slidable and rotary parts



Jan. 19, 1954 M. R. G. TEISEN 2,666,420 DEVICE HAVING SLIDABLE AND ROTARY PARTS Filed Dec. 16, 1949 4 She ets-Sheet 1 I I D 10 2D an in 50 50 7U 80 N Jan. 19, 1954 M. R. e. TEISEN DEVICE HAVING SLIDABLE AND ROTARY PARTS 4 Sheets-Sheet 2 Filed Dec. 16, 1949 K fi/ ll/ lllllllllillllllllrll Man-W wan IN ve rag gllllllllllfillllaww U AVA/I l!!! A Will/ll/rIl/l/l/l/ITI/ /A IWIIAMUvIIIIIIIIIIIII/Mm 0.

Jan. 19, 1954 M. R. G. TEISEN DEVICE HAVING SLIDABLE AND ROTARY PARTS FiledDb. 16, 1949 4 Sheets-Sheet 3 Jan. 19, 1954 M. R. G. TEISEN DEVICE HAVING SLIDABLE AND ROTARY PARTS 4 Sheets-Sheet 4 Filed Dec. 16, 1949 1 bJM-M H98; wwa,

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Patented Jan. 19, 1954 UNITED STATES DEVICE HAVING SLIDABLE AND ROTARY PARTS Mogens Roesdahl Groth Teisen, Copenhagen, Denmark, assignor to Henning Nielsen and Borge Nielsen, both of New York, N. Y., as joint assignees Application December 16, 1949, Serial No. 133,258

1 '2 Claims.

This invention relates to devices having slidable and rotary parts coupled together for the transfer of motion therebetween. Examples of such devices are internal combustion engines, steam engines, hydraulic and pneumatic motors, pumps, compressors, motor compressors and the like.

Dne object of the invention is to-provide a smoothly running device of the character described in which new and useful relationships are established between the movements of various parts.

Another object of the invention is to provide a device as above defined and in which vibrations resulting from both torque reaction and static and dynamic unbalance are reduced as compared with known similar devices.

A further object of the invention is to so construct a device having slidable and'rotary parts coupled together that in operation a state of;-

torque reaction balance and at the same time substantially complete dynamic balance is obtained, i. e. a state in which all acceleration forces occurring in the device are substantially at equilibrium at all times.

-A still further object ofthe invention is to devise a simple and reliable piston engine having two oppositely rotating output shafts.

A still further object of the invention is to provide a power transfer system by which the pistons of an internal combustion engine are automatically caused to oscillate about their "l'ong itudinal axis while performing their reciproca't I ing movements. 7 vention, it is a further object, where the engine is of the two-stroke type, to make use of the said automatically induced oscillation of the pistons for suitably timing the control of the inlet and outlet cylinder ports.

With these and other objects .in view which will appear as the description proceeds the invention consists in the novel arrangements and combinations of parts described in detail in the following specification with reference to some 7 specific embodiments of the invention and set forth in their general aspect in the appended claims.

Reference will now be had to the accompanying drawings in which Fig. 1 shows a basicmodel serving to the principles of the invention,

Fig. 2 a diagram for explaining some aspects of the mode of operation of the device illustrated in Fig. l,

Fig. 3 a vertical section through one form "of an internal combustion engine constructed in accordance with the invention,

Fig. 4 a vertical section along the line IVIV of Fig. 3,

illustrate In this embodiment of the in- Fig. 5 a horizontal section along the line VV of Fig. 3,

Fig. 6 a diagram illustrating the opening and closing-of various ports of the engine of Figs. 3-5,

Fig. 7 a vertical section through another form of an internal combustion engine constructed in accordance with the invention,

Fig. 8 a section along the line VIII-47111 of Fig. '7,

Fig. 9 a section along the line IX-IX of Fig. 8, and

Figs. 10 and 11 diagrams illustrating the opening and closing of the admission and exhaust cylinder ports of the engine of Figs. L9.

Referring first to Fig. 1, it is to be understood that this figure is purely diagrammatical and is intended to show a physical model for demonstration purposes rather than a device for any practical use. i is a rod mounted for sliding movement in two stationary guides 2 and 3, and i and tare shafts mounted for rotation in stationary journals or bearings 6, l and 3, 9 respectively. A disc Ni, ii is rigidly mounted at the end of each shaft 4, 55 facing the rod 5. A crossbar i2 is carried by the bar 5 and extends freely through-holes l3 and M in the discs l8 and M respectively, so that the crossbar cannot only slide in the said holes but is also free to oscillate so as to assume any angular position relative to the planes of the discs it and i i An examination should first be made of the various ways in which a device constructed according to the principles of Fig. 1 may be utilized for the transfer or control of motion. It will be understood that if the bar l reciprocates, the discs it and ll will rotate in opposite directions, and the crossbar, :2 will oscillate about the axis of the rod 5, While moving forth and back therewith.

Now, .it will easily be seen that if the discs 55 and l i rotate at a constant angular velocity, the rod i will reciprocate according to a harmonic function, i. e. a mathematical function of the [6:110 Sil'rwt. Thus the device may be used for controlling reciprocating parts whenever a harmonic motion oi the latter is desired.

Ii power is applied to one end or both ends of the rod 4, e. by connecting these ends to the pistons of an internal combustion engine or other engine, .powermay be taken oil from either of the shafts i and .5, or selectively or simultaneously from both with opposite directions of rotation. .inzthis application, the device replaces the conventional crankshaft arrangement while adding considerable advantages thereto as will be .iurther explained in the .following.

Conversely, if rotary power is applied to either of the shafts A and 5 or to both with opposite directions of rotation, reciprocating power may be talzen off at either or both ends of the red I, and this may e. g. be utilized for pumps or compressors.

Also, it would be possible to apply reciprocating power at one end of the rod E and to take off power the other end thereof in which case we have a system applicable to e. g. motor compressors, or one of the shafts t and may be used as an input shaft and the other shaft as an output shaft, whereby the device can be used for reversing a direction of rotation. Generally speaking, the two shafts i and 5 and the two ends of the rod i may be used for input or output in any possible combination.

As regards the crossbar i2, the oscillation thereof about the axis of the rod I may be utilized, e. g. in the case of an engine with pistons connected to the ends of the said rod, b making the connection between the crossbar l2 and the rod i and between the latter and the pistons rigid against relative rotation, so that the pistons are caused to oscillate about their axis during their stroke, whereby a more uniform wear is obtained, certain. useful control functions are made possible, as will hereinafter be described.

Consideration will now be given to the forces occurring in the device of Fig. l and more particularly to the vibrations that may result from the e forces. For the purposes of this examination it will be assumed that the rod 5 represents the piston rod of a one cylinder internal combustion en ine. As is well known, the main sources of vibration of such an engine are torque reaction and static and dynamic unbalance. As regards torque reaction, the vibration are due to the fact that since the input power varies be tween positive and negative values during each cycle while the load is assumed to be constant there will be a considerable variation of the torque reaction on the frame of the engine. In conventional engines, these variations can only be reduced by using a plurality of cylinders. However, when the conventional crank arrangement is replaced by the cinematic system of Fig. l, the torque reaction will be constant (assuming a constant load and su icient physical masses to keep the angular velocity of the output shafts constant) even if the engine has only one cylinder. To see this, it will first be assumed that there are equal loads on the shafts Z3 and 5 each representing a certain torque T, acting in opposite directions, say clockwise on the shaft i and counterclockwise on the shaft 5. In these circumstances, and provided the whole arrangement is symmetric about the axis of the rod i, the torque reactions from the two shafts will obviously be at balance in each instant, so that the resulting torque reaction will be constantly zero. Now, if an additional constant clockwise torque T is imparted to both shafts 4i and 5, this will change the resulting torque reaction from zero to the constant value 21', while at the same time the load on the shaft 5 disappears and the load on the shaft l is doubled. Thus, we have the engine running with only one output shaft loaded and constant torque reaction. Similarly, it will be seen that no matter how the output shafts 4 and 5 or any of them is loaded, as long as the load and the angular velocity are constant, the torque reaction will be constant and thus will not cause vibration. This is the condition referred to herein as torque reaction balance.

As regards vibrations from static unbalance, it is well known that such vibrations can easily be avoided byso constructing the movable parts of an engine that there will be no displacement of the resulting center of gravity during a cycle of the engine, and this of course also applies to an engine constructed in accordance with the invention.

Vibrations resulting from dynamic unbalance are a little more difficult to eliminate, but one important feature of the invention is that by constructing the rotors represented in Fig. l by the discs if and i i and their shafts i and 5 with excentrically disposed physical masses of a suitable size and location, a state of approximate dynamic balance may be obtained. In Fig. 1, the said physical masses are represented b a concentrated mass m secured to each of the discs ill and H diametrically opposite to the h les I3 and it thereof respectively.

To check the balance of the acceleration forces, it will suffice to consider the projections of these forces on two planes, viz. partly the plane defined by the axisof the bar 5 and the shafts i and 5, and partly a' plane perpendicular to the axes of the bar i. These two projections will be referred to hereinafter as horizontal and vertical respectively.

Obviously, the discs in, ii and shafts 5 can be disregarded in checking the dynamic balance. Considering first the horizontal projection, we have the masses m moving to and fro synchronously on opposite sides of the axis A. of the rod A, while the crossbar i2, the rod and the parts reciprocating therewith, such as pistons connected to the rod 5, can be represented by a concentrated mass M moving to and fro in opposite phase. Assuming that the discs it and ii rotate at a constant angular velocity d.0 I d.t and that the masses m are located at a radius r and the holes it and i l at a radius R, then the horizontal projections of all acceleration forces combine to a single force acting along the axis A and having the size Pn': (ZTTLT-MR) cos wt" In the vertical projection we have the masses m moving up and down in counterphase, combining to an acceleration moment about the axis A of the value 21m" sin wi'a-w where 2a is the distance between the discs 8 and 9.

Further, we have the crossbar l2, and possibly the rod I and the piston or pistons connected thereto oscillating about the axis A, resulting in. an acceleration moment of the value -I-f (wt) :0

Where I is the moment of inertia of the oscillating parts, and (wt) is a cyclic function that is not exactly a harmonic function.

Now, if we determine a harmonic function It sin wt coming as close as possible to flat) we can write f(wt):7c (sin wt-i-gwfl) and the resulting acceleration moment about the axis A then becomes Now, if m, r, R, a and I are so selected that then we: get

' Pn:' and Thus; we'have-complete dynamic-balance in horizontal projection; while in vertical projection we have only approximate dynamic balance, since there remains a residual dynamic unbalance of the value However, it has been found that this residual dynamic unbalance can be made so small that iti's e. g. possible to construct a one cylinder engine according to the invention with a total amount of vibrations resulting from all sources of the same order as in a six cylinder engine of the conventional design.

' It should be understood. that if difliculty is encountered from some reason of construction to make the distance a small enough to satisfy the above equations, each of the single masses m may be replaced by two masses arranged in diametrically opposite andaxialiy spaced positions. As is well known, two such masses may be represented by a single virtual concentrated masslocated at a smaller distance a from the axisA. Again, if the masses are not concentrated but distributed, as is o1"- course always the case in practice, a mathematical reduction can be made along well known principles.

The invention also provides additional means whereby the residual dynamic unbalance can becompletely eliminated. In Fig. 1, such means are shown in the form of cams land l5 mounted on the shafts 4 and 5 respectively, and vertical bars IT and I8 slidably mounted in guides l9 and 26' respectively and having their lower ends engaged with the earns and I6 and their upper ends engaged with the ends of a lever 2! mounted for oscillation about an axis parallel tothe axis A of' the bar l. As will be seen, when the shafts [and 3 rotate, the bars I? and i8 will move up and down in counterphase and the lever 26 will oscillate about its axis. In this manner an additional acceleration moment will be created in the vertical projection, and since the shape of the cams i5 and is may be selected at will, the additional acceleration moment may be made to match the residual dynamic unbalance.

This is illustrated in Fig. 2, where I represents the function I rout) referred to above, and II is a harmonic function selected arbitrarily within reasonable limits. III is a graph representing the difference between thefunctions I and II in each instant, and all that is necessary to ensure the possibility of obtaining complete dynamic balance is now to so construct the additional structure that the total acceleration moment thereof will follow the graph III.

In the horizontal projection, the additional means will not disturb the possibility of obtaining complete dynamic balance since the acceleration forces of the bars I1 and I8 and'the lever 2t have no components in the horizontal plane, and the cams l5 and it simply enter as component parts of the total masses of'the rotors and thus can be taken care of in the construction of the rotors to bring" about suitable values of m, rand a for the virtual concentrated masses thereof.

It will be understood. that the. additional cs cillating system might also. be made up. of the cams l5 and It and the bars: l7. and. H3 alone,

andthat it-is-immateriahwhether; theadditional oscillating system. is operated from. the shafts; 2' and 3:ass shown, or from the oscillating bar I,

In these figures, 3-! is a piston slidably androtatably mounted in a cylinder 32, while 33 and 3.4 are two shafts rotatably mounted in covers 35' and. 3.8 combining with the cylinder 32 to form an engine casing- The two shafts 33 and 3 3 are co-axial and disposed at right angles to the piston 3|. Each. shaft carries an excentricdisc 3? and 38 respectively, on which there is mounted a twov part shell 39, cc respectively forming a spherical seat for a spherical member ll, 32 in which the respective ends of a connecting lever 43 extending throughan-d secured in a transverse bore M of the. piston. 3! are slidably engaged.

It will easily be seen that the piston 3i and the shafts 33. and 34' coupled together by means of' the connecting lever 43 and the universal joints formed by the shells 39, 4d and spherical members 4| and. 42 form a cinematic system exactl y similar to. that. shown in Fig. l, disregarding the residual dynamic unbalance eliminating means shown in the latter figure. In this connection, it is observed that the excentric discs 31. and 38 represent the excentrically disposed concentrated masses of Fig. 1. In the example shown, the excentrici-ty thus establishedis combined with an opposite excentricity of fly-wheels 45 and 48. mounted on the shafts 3-3 and 3d respectively, the latter excentricity being provided by boring holes 41 and 48 at a suitable point of each of the flywheels 45 and 45. The principles of combining excentricities for the purpose of adjusting dynamic balance have been outlined above.

It will be seen that the piston 3! while moving to and fro in the cylinder 32 will at the same time .be rotated back and forth about its own axis. This tends tov make the. wear on the piston and cylinder more uniform, and moreover, the rotary movement-of the piston is utilized in the embodiment shown for establishing an advantageous control of the admission and exhaust to and from the cylinder; as will now be explained.

The piston 3! is hollow and has a top wall it and. a bottom wall 59, the cylindrical wall of the piston extending beyond the latter in the form of a skirt. 5! slidable in the space 52 between the cylinder wall and an inverted cupshaped end closure 53 provided at the bottom of the cylinder. The space above the'top wall id-of the piston forms the activecylinder space while the space between the bottom wall 5 3 of the piston andthe wall 54 of the bottom closure 53 forms a pumping chamber.

The cylinder wall is provided with a number of. ports via; a carburettor port 55 communicating with the carburettor 56, two transfer ports 5! communicating with the interior of the engine casing, four admission ports 58 communicating with twointermediate ports 59 through passages in the cylinder wall, four exhaust ports 6! communicating with the atmosphere or an exhaust manifoldnot shown, and two large openings. 62 providing the necessary space for the movements of. the. connecting lever 43 and at the sametime establishing. a. free; communicatiorr. from the interior; of. the engine casing to the interior of the piston 3! through a plurality of openings 63 in the latter at such times as is necessary.

The control of the pumping efiect in the lower part of the cylinder is performed by two ports 54 in the piston 3! in connection with the cylinder ports 55 and 51.

The diagram of Fig. 6 illustrates the cycle of the piston 3!, the uppermost and lowermost points of the circle shown in that figure corresponding to the top and bottom dead centre respectively. Starting now e. g. from the bottom dead centre, in which position the bottom wall 50 of the piston 3! is closest to the wall 54, it will be understood that when the piston has passed that position, it commences its upward stroke and thus tends to create a vacuum in the space between the walls 553 and 54. However, in the moment the piston starts its upward stroke, there will be a pressure in the pumping chamber between the said walls, and it is there.- fore arranged that the carburettor port 55 is opened by co-operation with the port it of the piston only in a point C. 0., Fig. 6, slightly after the bottom dead centre so that there will be no risk of blow back into the carburettor. The carburettor port 55 now remains open during the upward stroke of the piston so that carburetted fuel is sucked into the pumping chamber, and immediately after the piston has passed the top dead centre, the carburettor port 55 is closed in ie point CC. in Fig. 6, and shortly afterwards the transfer port 5i is opened in the point T. O. I

and remains open during the downward stroke of the piston until it is closed in the point '1. C.

corresponding to the bottom dead centre, so that during the downward stroke of the piston carburetted-fuel is pumped from the pumping chamber through the transfer port 57 into the interior of the engine casing. It is to be noted that this simple and functionally correct control of the carburettor and transfer ports by means of two ports of the piston is possible only owing to the combined translational and rotary movement of the piston.

The control of the admission and exhaust to and from the active cylinder space above the top wall it of the piston is effected partly by the top edge of the piston and partly by two ports 65 in the wall of the piston in conjunction with the cylinder ports 5%) and 6!. During the downward stroke of the piston, the top edge thereof will first start uncovering the admission ports 58 in the point A() in Fig. 6, but since at this time the ports have not yet started uncovering the ports 59, there will not yet be any admission of fuel to the cylinder. A moment later, viz. in the point E0 in Fig. 6, the top edge of the piston starts uncovering the exhaust ports 5!, and only after these ports have been opened for a while do the ports es start uncovering the ports 59 in point A0 thereby establishing admission of fuel to the cylinder via the interior of the piston from the interior of the engine casing, to which fuel is at the same time supplied under pressure from the pumping chamber below the piston.

During its upward stroke the top edge of the piston 3i will first close the exhaust openings 6! in the point EC in r'g. 6. In this phase the piston has been turned through such an angle that the ports 65 still keep the port 5?) open and accordingly there will still be admission of carburetted fuel to the cylinder. The admission is closed only in the point AC where the top edge ports at and 92.

sectors while the admission ports of the piston 3| reaches the level of the top edges of the admission ports 58. Somewhat later, viz. in the point AC, the ports 65 will close the ports 59, but this is of course of no importance at this time, because the admission has already been cut off by the co-operation of the top edge of the piston 3! with the admission ports 58.

Here again, it will be seen that thanks to the rotation of the piston, it has been possible to obtain an unsymmetric timing diagram, i. e. a diagram in which the exhaust is both opened and closed before the admission in contradistinction to a symmetric timing diagram where the exhaust is opened before and closed at a corresponding phase angle after the admission.

The embodiment illustrated in Figs. 7-11 comprises a piston H slidably mounted in a cylinder 12 and coiipled to a pair of shafts l3, i l carrying excentric discs ll, 13 by means of a connecting lever $3, and spherical members 8!, 82 seated in two part shells lit, 85 in exactly similar manner as in the first embodiment. However, in the embodiment of Figs. 7-11, the piston ii is effective at both cylinder ends, so that it constitutes in effect two aligned pistons of ie counter-phase type operating in aligned cylinders formed by the two ends of the cylinder l2. Considering now one of the two cylinder units thus formed, it will be seen from Fig. 9 that the cylinder wall is provided with a plurality of alternately arranged admission ports 9% and exhaust ports 92 uniformly distributed over the circumference of the cylinder wall, the admission ports ti communicating with a compressed air passage 93 referred to in the following, and the exhaust ports communicating with an exhaust manifold il l. The piston end is constructed with alternating elevated sectors 95 and recessed sectors 96, each sector occupying an angle equal to the angular spacing of neighbouring The co-operation of the said sectors with the admission and exhaust ports 33 and 92 to control opening and closing thereof is illustrated in Fig. 11, while Fig. 10 illustrates the cycle of the piston similarly as in Fig. 6. In ll, the admission and exhaust ports are by the letters A and E respectively while the top edge of the piston is marked by a line PE with underlying hatching. the graph (1 of Fig. 11, corresponding to the position E. O. in Fig. 10, it is seen that the exhaust ports E are uncovered by the recessed piston sectors while the admission ports are not yet opened because at this stage they register with elevated piston sectors. In the point A. O. of 1G represented by the graph in of Fig. 11, the admission ports are opened by the elevated piston sectors. In the bottom dead centre B. D. 0., the piston has been so much turned that the elevated piston. sectors are now midway between the admission and exhaust ports as illustrated in the graph 0 of Fig. 1'1. On further movement of the piston, the elevated piston sectors are displaced still more towards the exhaust ports, and in the point E. C. the latter are closed by said elevated remain open as illustrated in the graph d or Fig. 11, until they are closed by the recessed piston sectors in the point AC as illustrated in the graph e of Fig. 11. Thus, by the combined reciprocating and turning movement of the piston it is obtained that the admission ports lag a little behind the exhaust ports both in the opening and in the closing phase, or in other words, we have an asymmetric timing diagram similarly as in the first embodiment. V

The construction of the piston ends with alternate elevated and recessed sectors also serves to establish favourable conditions of flow both in the scavenging and in the injection phase. In the latter phase, as will be seen in the left hand portion of Fig. 8, the elevated sectors come very close to the conical cylinder top so that the cylinder space is subdivided into a number of sectors formed by the recessed piston sectors. Now, the injected fuel is split up in jets in each of said sectors, and since the piston is at the same time turned, the individual jets are thereby caused more or less to sweep the whole area of the respective sectors so that a good distribution of the fuel is obtained.

To supply air under pressure to the admission ports; use is made of a special charging pump which at the same time embodies the residual dynamic .unbalance eliminating feature of Fig. 1. The charging pump comprises a vane 91 formed with a central hub 98 and mounted for rotation between cylindrical seats 93 and I at the middle of an elongated casing IM and having its ends and sides in air-tight contact with sealing strips I02 at the ends and sides of the casing so as to subdivide the interior of the casing IOI into an upper right hand chamber I03, an upper left hand chamber I04, a lower right hand chamber I05, and a lower left hand chamber I05. The two upper chambers I03 and I04 communicate with the atmosphere through individual inwardly opening flap valves I01 and I08 respectively and a common air filter I00, while the two lower chambers I05 and I06 are in constant communication withthe passages 93 leading to the admission ports of the respective cylinders. The upper right hand chamber I03 is in constant communication with the lower left hand chamber I06 through a passage H0 in the vane 91, and similarly the upper left hand chamber I04 is in constant communication with the lower right hand chamber I05 through a passage III in the vane 91.

The vane 91 is located with its axis of rotation vertically above and parallel to theaxis of the cylinder 12 and piston H and is engaged from below near its ends by two slidably mounted lifters I I 2, I I 3 each provided with a roller I I4, I I 5 in contact with a cam H6, H1 on one of the shafts'13, 14. Each lifter H2, H3 comprises a hollow body portion H8 and a cover H9, and in the case of one of the lifters these two elements are mounted with a small clearance for relative axial movement, and are urged apart by means of a compression spring I housed between them and serving to accommodate inevitable small inaccuracies of all the co-operating parts here considered. a

It will easily be seen that when the engine is running, the vane 91 is caused to oscillate in its casing IM and will thereby alternately create a suction and a compression effect in each pair of chambers I03, I06 and I04, I05, whereby each pair of chambers will suck in fresh air during one half cycle and compress such air during the following half cycle and is thus ready to supply air under pressure to its appertaining cylinder during the scavenging and supercharging period thereof, which falls during the latter half cycle, the admission ports 9| of the cylinder 12 serving at the same time as outlet controls for the respective pairs of chambers.

Moreover, it will be seen that the structure 10 formed by the vane 91, the push rods I I2, I I3 and the cams H6, H1 is exactly similar to the structure 2|, I1, I8, I'5, I6 of Fig. 1 so that by suitably dimensioning the parts 91, H2, H3, H6, H1 complete dynamic balance of the engine may be obtained.

I2 I, I22 are two coupling halves geared to the two shafts 13, 14 and selectively engageable with two coupling halves I23, I24 on an output shaft I25 by means of a servo-motor I23 so that the output shaft I 25 may thereby be caused to rotate in one or the other direction at will.

I claim:

1. ,A two stroke internal combustion engine comprising a cylinder, reciprocating means including a piston slidable in said cylinder, a pair of rotors mounted on opposite sides of the axis of said piston for rotation about a common axis perpendicular thereto, connecting means extending transversely from said reciprocating means and engaged with said pair of rotors for the transfer of motion circumferentially thereof, said rotors comprising excentrically disposed physical masses of a size and location to create, in conjunction With the physical mass of said reciprocating and connecting means, complete dynamic balance as projected on a plane defined by the axis of said piston and the common axis of rotation of said rotors, and partial dynamic balance as projected on a plane perpendicular to the axis of said piston, and a charging pump for said cylinder including a pumping vane mounted for oscillation about an axis parallel to the axis of said piston and operatively coupled to said system of reciprocating means and rotors, said oscillating means being constructed to substantially eliminate residual dynamic unbalance as projected on a plane perpendicular to the axis of said piston.

2. A two stroke internal combustion engine comprising a pair of aligned cylinders, reciprocating means comprising a piston slidable and rotatable about its axis in each of said cylinders, a pair of rotors mounted on opposite sides of the common axis of said pistons for rotation about a common axis of rotation perpendicular thereto, connecting means rigidly connected with said reciprocating means and extending transversely thereof and engaged with said pair of rotors at a distance from the axis thereof for the transfer of motion circumferentially of said rotors, each of said cylinders having inlet and outlet passages arranged to be controlled by the respective pistons and so located and shaped as to create an asymmetric timing diagram owing to the combined reciprocating and rotary movement of said pistons in their respective cylinders, and a chargmg pump for said cylinders including a pumping vane mounted for oscillation about an axis parallel to the axis of said pistons and operatively coupled to said system of reciprocating means and rotors, said oscillating means being constructed to substantially eliminate residual dynamic unbalance as projected on a plane perpendicular to the axis of said pistons.

MOGENS ROESDAHL GROTH 'IEISEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 570,871 Douthett Nov. 3, 1896 1,614,819 Bauer et al Jan. 17 1927 1,619,696 Bowen Mar. 1, 1927 2,065,688 Gehres Dec. 29, 1936 

